JP3982766B2 - Stepping motor control device - Google Patents

Description

  The present invention relates to a stepping motor control device that performs positioning control in accordance with a pulse train position command, and more particularly to a microstep control device for a stepping motor.

JP, 6-343294, A There is the thing indicated in JP, 6-343294, A as a drive device of a stepping motor conventionally. FIG. 5 shows a configuration of a conventional stepping motor driving apparatus.

In FIG. 5, 59 is a stepping motor, 51 is an up / down counter for counting up or down a pulse train command P * applied from the outside in accordance with a rotation direction signal U / D, and 52a and 52b. Is a ROM storing excitation signal data corresponding to the count value of the up / down counter 2, 53a and 53b are D / A converters for converting ROM data into voltage signals, and 54a and 54b are for amplifying the voltage of the D / A converter. This is a drive amplifier for driving the stepping motor.

  In the above configuration, the count value of the up / down counter is converted to the address of the ROMs 52a and 52b, and the data of the ROMs 52a and 52b searched by the address value are converted into voltage and applied to the stepping motor. Here, the data of the ROMs 52a and 52b is changed to a pseudo sine wave, and the stepping motor can be smoothly rotated by increasing the number of divisions in one period of the pseudo sine wave.

  However, in the above conventional configuration, in order to smoothly rotate the stepping motor, it is necessary to drive the ROM with the number of divisions of one pseudo sine wave cycle, and the position information of the host controller is also the number of divisions of one pseudo sine wave cycle. It is necessary to match (position movement amount / command 1 pulse). For this reason, when it is desired to drive the stepping motor at high speed, it is necessary to increase the frequency of the pulse train command output from the host controller, and without using an expensive host controller that can output a pulse train command having a high frequency accordingly. There was a problem that we should not do. Also, if you want to drive the stepping motor at a high speed with a low-frequency pulse train command, you can reduce the number of divisions in one pseudo sine wave cycle, so the stepping motor cannot be smoothly rotated at low speeds. There was also a problem that vibrations occurred.

  The present invention solves the above-described conventional problems, and generates microstep data with high precision at a constant sampling period that is asynchronous with a pulse train command applied from the outside to a microcomputer, etc. An object of the present invention is to provide a control device for a rotating stepping motor.

  In order to solve the above-mentioned problems, the present invention provides a stepping motor drive device for energizing a sinusoidal staircase current in accordance with a pulse train command applied from outside, a counter for counting the number of steps of the pulse train command and converting it into a position command; A latch circuit that holds the count value of the counter, a reference signal generator that generates a latch signal and a reference clock signal of the latch circuit, and a time interval from the generation of a pulse train command to the generation of the latch signal is measured with the reference clock signal Command pulse interval information measured by a counting circuit for measuring the number of steps of the pulse train command and the counting circuit for measuring the pulse interval of the pulse train command. And a counting circuit that measures the time interval from the generation of the pulse train command to the generation of the latch signal. The position command correction value is calculated using the time difference information, the correction value is added to the number of steps of the pulse train command when the stepping motor is driven, and the pulse interval of the pulse train command is measured with the reference clock signal when the stepping motor is stopped. The correction value of the position command is set to zero from the overflow information of the counting circuit and added to the number of steps of the pulse train command to perform microstep driving.

  Thereby, even when the stepping motor is driven by a position command with a low (rough) microstep resolution, the stepping motor can smoothly rotate in the low speed region and reduce vibration.

  FIG. 4 is an explanatory diagram showing the relationship between the pulse train command and the position command. (A) shows that the position command has the meaning of θ * (m−1) when the pulse train command P * (m−1) is applied. (A ') indicates that the position command has the meaning of θ * (m) when the pulse train command P * (m) is applied. (A ″) indicates that the position command has the meaning of θ * (m + 1) when the pulse train command P * (m + 1) is applied. The conventional stepping motor driving apparatus is vibrant because the motor operates in accordance with a position command having a step-like locus with the step angle per pulse of the pulse train command as θd. In addition, (a) with respect to (a) is the case where the position command is sampled with the sampling pulse t (n), and similarly (a ′) with respect to (a ′), the position command is with the sampling pulse t (n + 6). In the same way, (i '') for (a '') shows the case where the position command is sampled by the sampling pulse t (n + 13), and T2 (n) for (a). ), (A ′) are shifted in time by T2 (n) ′, and (a ″) by T2 (n) ″. When the stepping motor rotates at an average rotational speed ω = θd / T1 (n), the position command is considered to be a position advanced by Δθ (n) instead of θ (n) at the time t (n). Therefore, the position of (c) is desirable. That is, an error of Δθ (n) occurs when the position command θ (n) given by the pulse train command P (n) is sampled by the sampling pulse t (n). This sampling error has a problem that since the pulse train command and the sampling pulse are asynchronous, the sampling error changes every sampling and a vibration component is generated in the command.

なお，例えばパルス列指令θ＊（ｍ）が入力される前にサンプリングパルスｔ（ｎ＋１）〜ｔ（ｎ＋５）が発生した場合には，数１におけるＴ２（ｎ）に対してＴ２（ｎ＋１）〜Ｔ２（ｎ＋５）を用いて，図４の（ウ’）で示す状態に補正するようにする。また，ステッピングモータ停止時には，補正値を零としてパルス列指令の１パルスあたりのステップ角θｄの倍数の位置に停止するようにする。 Therefore, the interval between the pulse train commands P * (m−1) and P * (m) is estimated by, for example, Equation 1, and the position command is corrected by Equation 2 with respect to the original position command.
Where Δθ (n) is a position command correction value, T1 (n) is a count value indicating a pulse train command interval, T2 (n) is a count value indicating a time interval from the generation of the pulse train command to the generation of a latch signal, θd Is a step angle per pulse of a pulse train command applied from the outside, θ * (n) is a value obtained by counting the pulse train command and converting it to a position command, and θc (n) is a position command after correction.

For example, when the sampling pulses t (n + 1) to t (n + 5) are generated before the pulse train command θ * (m) is input, T2 (n + 1) to T2 with respect to T2 (n) in Equation 1. (N + 5) is used to correct the state shown in FIG. When the stepping motor is stopped, the correction value is set to zero and the stepping motor is stopped at a position that is a multiple of the step angle θd per pulse of the pulse train command.

  The control device of the present invention corrects by dividing the step angle per pulse of the pulse train command by the sampling period when the stepping motor is driven at a low speed, and smooth rotation without vibration is obtained. In addition, since the sampling error of the position command can be reduced, stable sampling processing can be realized by suppressing fluctuation of the pulse train command over a wide rotation range. Therefore, the stepping motor can be smoothly rotated without increasing the processing speed of the microcomputer or the like.

  The best mode for carrying out the present invention is a stepping motor control device that performs positioning control according to a pulse train position command, and more particularly, a device related to microstep control of a stepping motor.

FIG. 1 shows an embodiment of the present invention, where 10a is a direction command input terminal, 10b is a pulse train command input terminal, 20a and 20b are first and second phase current command input terminals, and 1 is a position from the pulse train command. Counter unit for converting to command, 2 is a position command corrector, 5 is an adder, 6 is a multiplier, 3 is a current command generator, 4 is a current controller, 7 is an inverter, 8a and 8b are the first phase and the first phase A two-phase current detector 9 is a stepping motor.
A position command corrector is added to the conventional stepping motor control device shown in FIG.
The operation of FIG. 1 will be outlined. A position command is applied to 10a and 10b in the form of a rotation direction and a pulse train from the outside, and the pulse train is converted into a position command θ * by the counter unit 1. The terminal 10c is an input terminal for a signal that determines the number of divisions of microsteps, and a step angle θd proportional to the rotation amount per pulse is set. The position command correction unit 2 receives the direction command input U / D and the pulse train command P * and outputs a correction amount Δθ. The corrected position command θ ** is divided into microsteps by multiplying the value θc obtained by adding the position command θ * and the correction amount Δθ by the adder 5 by the multiplier 6 by the step angle θd proportional to the rotation amount per pulse. The value corresponds to the number. Details of a specific example of the method of generating the correction position command θ ** will be described later. The current command generator 3 receives the current amplitude commands Iαp * and Iβp * set in the terminals 20a and 20b and the correction position command θ ** and outputs current commands iα * and iβ *.
The current controller 4, the inverter 7, and the current detectors 8 a and 8 b constitute a current control unit, and the motor applied voltage is controlled so that the energized currents iαf and iβf of the stepping motor 9 coincide with the current commands iα * and iβ *. Therefore, microstep drive is realized.

FIG. 2 is a detailed explanatory diagram of the counter unit 1 and the position command correction unit 2.
The counter unit 1 includes an up / down counter 11 and a latch circuit 12. The pulse circuit command is counted by the up / down counter 11 and is latched by a latch signal (signal synchronized with the sampling signal) Ts generated by the reference signal generator 25. Is converted into a position command θ *, which is a binary value, at regular intervals.
The position command correction unit 2 includes a timing pulse generation unit 21, a counter 22, a latch circuit 24a, a latch circuit 24b, a reference signal generation unit 25, a divider 26, and a sign switching unit 28.
The operation of the position command correction unit 2 will be described in comparison with FIG. The reference signal generator 25 generates a reference clock signal CKs and a latch signal Ts as control signals for the timing pulse generator 21, and the timing pulse generator 21 generates internal control timing signals pt1, pt2, and pt3.
pt1 is a signal obtained by sampling the pulse train command P * with CKs, and pt2 is a signal delayed in time by one pulse of CKs. Further, pt3 is a signal that becomes “H” at the falling edge of Ts and returns to “L” at the rising edge of CKs. Immediately after the pulse train command P * is input, the counter 22 is cleared at the rising edge of pt2, and thereafter the period until the next pt2 is generated is counted with CKs. The value of the counter 22 is held by the latch circuit 24a at the timing of the rising edge of pt1 immediately before the counter 22 is cleared. Therefore, the output T1 of the latch circuit 24a holds a value corresponding to the time interval P *.

The latch circuit 24b holds the value of the counter 22 at the timing of the rising edge of pt3. The rising edge of pt3 substantially coincides with the rising edge of Ts, and the output T2 of the latch circuit 24b holds a value corresponding to the time from when P * is input until Ts is generated.
The divider 26 divides the output T2 of the latch circuit 24b by the output T1 of the latch circuit 24a, and the sign switching unit 28 converts the output of the divider 26 into signed information corresponding to the rotation direction, thereby obtaining a correction amount Δθ. . In the motor stop state where the pulse train command P * is not input, the counter 22 overflows and outputs an overflow signal OVFs to clear the divider 26. Note that θd in Equation 1 is the step angle per pulse of the pulse train command, and therefore corresponds to the minimum change amount of the latch circuit 12. Therefore, since θd in Equation 1 when adding to the output θ * of the latch circuit 12 is 1, the output of the sign switching unit 28 corresponds to the result of executing the operation of Equation 1.
A value obtained by adding the position command θ *, which is the output of the latch circuit 12, and the correction amount Δθ, which is the output of the sign switching unit 28, by the adder 23 corresponds to θc which is the calculation result of Equation 2, and Δθ is θ *. [Theta] c is a value obtained by linearly interpolating the lower bits of [theta] * and extending.

The multiplier 6 is provided to multiply the output of the adder 5 by θd and convert it into a corrected position command θ ** corresponding to the number of microstep divisions. That is, the output of the multiplier 6 is the input of the current command generator 3, and is used as address information for searching the amplitude data of the sinusoidal current command. For example, when θd = 1 and θd = 2, the latter is 1 pulse. Since the change in the per-address is doubled, it is rotated at a step angle twice that of the former.
Although not clearly shown in FIGS. 1 and 2, the latch signal Ts of the reference signal generator 25 is obtained by dividing the reference clock signal CKs, and can be sampled by synchronizing with a motor control cycle of a microcomputer or the like. It is possible to configure a motor control device that reduces vibration components associated with processing.

The present invention can be used not only for a stepping motor control device for position control but also for a stepping motor speed control device that uses a pulse train as a command, an AC servo motor position control device that uses a pulse train as a command, and a speed control device. is there.
Further, although the pulse train command form is shown by way of example as a direction signal and a pulse train, it can also be applied to other command forms such as a direction-specific pulse train command and a two-phase rectangular wave pulse train command.
The present invention is intended for a motor control device that performs control using a microcomputer or the like, but is applicable to all control devices that perform sampling processing on signals input asynchronously from the outside.
In addition, the present invention is often applied to a hardware configuration device as well as a software hardware processing device, although a control device that performs sampling processing is often equipped with a microcomputer to perform software processing. .

It is explanatory drawing which showed the Example. It is detailed explanatory drawing of an Example. It is operation | movement timing explanatory drawing of the detailed explanatory drawing of an Example. It is a principle explanatory view of the present invention. It is explanatory drawing of the conventional stepping motor drive circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Counter part 2 Position command correction | amendment part 3 Current command generation part 4 Current controller 5 Adder 6 Multiplier 7 Inverter 8a, 8b Current detector of 1st phase and 2nd phase 9 Stepping motor 10a Direction command input terminal 10b Pulse train command Input terminal 11 Up / down counter 20a, 20b First and second phase current command input terminals 21a, 21b, 21c Flip-flop (for generating timing pulse)
22 Counter 24a, 24b Latch circuit 25 Reference signal generator 26 Divider 28 Sign switching unit 51 Up / down counter 52a, 52b ROM
53a, 53b D / A converter 54a, 54b Drive amplifier 59 Stepping motor

Claims (1)

In a stepping motor driving apparatus for energizing a sinusoidal staircase current in accordance with a pulse train command applied from outside, a counter for counting the number of steps of the pulse train command and converting it into a position command, and a latch circuit for holding the count value of the counter A reference signal generator for generating a latch signal and a reference clock signal of the latch circuit, a counting circuit for measuring a time interval from generation of a pulse train command to generation of a latch signal by the reference clock signal, and a pulse interval of the pulse train command A counting circuit for measuring with the reference clock signal, the number of steps of the pulse train command, the command pulse interval information measured by the counting circuit for measuring the pulse interval of the pulse train command, and from the generation of the pulse train command to the generation of the latch signal Position command using time difference information measured by a counting circuit that measures the time interval of The correction value is calculated and added to the number of steps of the pulse train command when the stepping motor is driven, and the pulse circuit command pulse interval is measured by the reference clock signal when the stepping motor is stopped. A control device for a stepping motor, wherein the correction value of the command is set to zero and is added to the number of steps of the pulse train command to perform microstep driving.

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